"Consideration of mental categories influences how content is organized, while factoring in visual perception, memory, semantic networks, and learning helps to guide labeling and interface decisions. Considering research and theory in cognitive psychology helps information architects create better user experiences, if only because it helps us ask more, and better, questions about what creates a good user experience."
http://www.boxesandarrows.com/view/cognitive_psychology_ia_from_theory_to_pra...